The doctrine of primary assumption of the risk bars liability for injuries caused by a negligent surfer to a fellow surfer because those injuries were caused by risks inherent in the sport of surfing.  Wipe-outs are common as are injuries from collisions with other surfers or their surf boards.  Surfers often violate unwritten rules of etiquette governing surfing and surf without having the board on a leash.  Fins on the bottom of the surf board are sharp and can cause injury when they impact a surfer.